Home » Ni et al. 2009

Reanalyses of the radiation belt electron phase space density using nearly equatorial CRRES and polar-orbiting Akebono satellite observations

Ni B., Y. Shprits, T. Nagai, R. Thorne, Y. Chen, D. Kondrashov, H. Kim, (2009), Reanalyses of the radiation belt electron phase space density using nearly equatorial CRRES and polar-orbiting Akebono satellite observations, J. of Geophys. Res. [Space Physics], 114, doi:10.1029/2008JA013933

Abstract

Data assimilation techniques provide algorithms that allow for blending of incomplete and inaccurate data with physics-based dynamic models to reconstruct the electron phase space density (PSD) in the radiation belts. In this study, we perform reanalyses of the radial PSD profile using two independent data sources from the nearly equatorial CRRES Medium Electron A (MEA) observations and the polar-orbiting Akebono Radiation Monitor (RDM) measurements for a 50-day period from 18 August to 6 October 1990. We utilize the University of California, Los Angeles, One-Dimensional Versatile Electron Radiation Belt (UCLA 1-D VERB) code and a Kalman filtering approach. Comparison of the reanalyses obtained independently using the CRRES MEA and Akebono RDM measurements shows that the dynamics of the PSD can be accurately reconstructed using Kalman filtering even when available data are sparse, inaccurate, and contaminated by random errors. The reanalyses exhibit similarities in the locations and magnitudes of peaks in radial profiles of PSD and the rate and radial extent of the dropouts during storms. This study shows that when unidirectional data are not available, pitch angle averaged flux measurements can be used to infer the long-term behavior (climatology) of the radiation belts. The methodology of obtaining PSD from pitch angle averaged and unidirectional fluxes using the Tsyganenko and Stern (1996) magnetic field model is described in detail.

Authors (sorted by name)

Chen Kim Kondrashov Nagai Ni Shprits Thorne

Journal / Conference

Journal Of Geophysical Research (Space Physics)

Acknowledgments

This work was supported by NASA LWS grant NNX06AB84G and by the Lab Fees Research Program. We are thankful for the use of the NSSDC OMNIWeb database of solar wind data and for the use of SSCWeb 3‐D Orbit Viewer software for satellite orbit plotting. We thank Howard Singer for providing the CRRES magnetic field data. We are also grateful for the use of the ONERA‐DESP codes provided by D. Boscher and S. Bourdarie and for useful discussions. B. N. thanks Y. Lu for help with FORTRAN problems. The authors would also like to thank Jerry Goldstein for useful comments and stimulating discussions.

Grants

NNX06AB84G

Bibtex

@article{doi:10.1029/2008JA013933,
author = {Ni, Binbin and Shprits, Yuri and Nagai, Tsugunobu and Thorne, Richard and Chen, Yue and Kondrashov, Dmitri and Kim, Hee-jeong},
title = {Reanalyses of the radiation belt electron phase space density using nearly equatorial CRRES and polar-orbiting Akebono satellite observations},
journal = {Journal of Geophysical Research: Space Physics},
volume = {114},
year = {2009},
number = {A5},
pages = {},
keywords = {data assimilation technique, phase space density, radiation belt electrons},
doi = {10.1029/2008JA013933},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2008JA013933},
eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2008JA013933},
abstract = {Data assimilation techniques provide algorithms that allow for blending of incomplete and inaccurate data with physics-based dynamic models to reconstruct the electron phase space density (PSD) in the radiation belts. In this study, we perform reanalyses of the radial PSD profile using two independent data sources from the nearly equatorial CRRES Medium Electron A (MEA) observations and the polar-orbiting Akebono Radiation Monitor (RDM) measurements for a 50-day period from 18 August to 6 October 1990. We utilize the University of California, Los Angeles, One-Dimensional Versatile Electron Radiation Belt (UCLA 1-D VERB) code and a Kalman filtering approach. Comparison of the reanalyses obtained independently using the CRRES MEA and Akebono RDM measurements shows that the dynamics of the PSD can be accurately reconstructed using Kalman filtering even when available data are sparse, inaccurate, and contaminated by random errors. The reanalyses exhibit similarities in the locations and magnitudes of peaks in radial profiles of PSD and the rate and radial extent of the dropouts during storms. This study shows that when unidirectional data are not available, pitch angle averaged flux measurements can be used to infer the long-term behavior (climatology) of the radiation belts. The methodology of obtaining PSD from pitch angle averaged and unidirectional fluxes using the Tsyganenko and Stern (1996) magnetic field model is described in detail.}
}